Refractive errors, such as myopia, hyperopia and astigmatism, are very common all over the world. Refractive surgery started in the latter half of the twentieth century and over the last one or two decades refractive surgery with lasers has become popular. Refractive surgery for myopia flattens the cornea of the eye and decreases its refractive power. Surgery for hyperopia on the other hand increases the curvature of the cornea and increases the refractive power. Today this is most frequently done with a lasik procedure where a flap is lifted of the cornea and the laser surgery performed underneath the flap.